Integrated circuit (IC) devices are often mounted onto a printed circuit board (PCB) to form a printed circuit assembly (PCA). The PCA may be a computer-processing platform of a mobile computer (e.g., laptop, or mobile phone), a desktop personal computer, a data processing rack server, or the like. The PCB typically includes multiple layers of conductive trace metallization interconnecting the various packaged IC devices and discrete components that are mounted to the board. PCB trace layers may be employed for power delivery and signal routing.
FIG. 1A depicts a plan view of a conventional ball-grid array (BGA) packaged-device 101 that is to receive power from traces on a PCB. BGA-packaged-device 101 includes a plurality of solder balls 105 that may provide power and ground connections or signal input/output (I/O) to one or more ICs contained within the package. In the illustrated example, power connections are grouped together within a BGA power corridor 110 extending from the outer package edge to near the center of the package. Land-side components (LSCs) 120 may also be disposed a various locations within the ball-grid array.
FIG. 1B depicts a plan view of a front side of a conventional PCB 102 configured to power conventional packaged-device 101. PCB 102 includes a power corridor 112 extending between front-side pads 126 that are to mount the power-source device (e.g., a voltage regulator) and a portion of front-side BGA pads 115 that are to be joined to BGA lands that are within BGA power corridor 110. FIG. 1C depicts a cross-sectional view through a conventional PCA 103 including a power-source device 125 and packaged-device 101 mounted to PCB 102. Depending on the complexity of the IC, packaged-device 101 may require as much as 50-200 W of power, requiring the use of all (e.g., 8) PCB metallization layers 135 (including signal routing layers) for power and ground routing within power corridor 112. Through-board vias 136 are employed at the ends of power corridor 112 to couple together the multiple PCB metallization layers. Grouping power connections within power corridor 112 enables full use of PCB metallization and has significant advantages in terms of a smaller form-factor relative to running an external cable between connectors at the power-source device 125 and power-sink device 101. However, enlisting PCB metallization layers in this fashion may require a greater number of BGA package connections to be assigned to the voltage supply than is needed for power delivery as determined based on an electrical current/pin specification. For example, limitations imposed on the weight of copper in the PCB metallization layers and/or limitations imposed on the number of metallization layers in the PCB aimed at keeping board costs down may ultimately reduce the number of BGA connections in packaged-device 101 available for signal assignment. Also, although power corridor 112 attempts to minimize the disruption and loss of signal routing paths by confining the portion of the PCB dedicated to the supply of power, I/O escape path routing is still negatively impacted.